Steam flooding, as a thermal enhanced oil recovery (EOR) process, has been introduced in heavy (5°-20° API) oil fields with high potential of recovery factor in relatively shallow and depleted formations. Heavy oils always have high viscosities that are 100 cp or greater in situ. Steam, through its latent heat, reduces the viscosity of the oil and makes the oil move toward the production wellbores such as by gravity drainage and viscous forces.
In thermal hydrocarbon production steam flooding operations, steam is typically generated above the ground and may be used to provide steam to one or several wells (e.g., injection wells, production wells undergoing cyclic steaming, etc.) at once. A plurality of tubulars (e.g., conduits) are installed within each well to deliver steam into the hydrocarbon bearing formation. Tubulars are inclusive of casing, liner, tubing, and conductor which are all different sizes of pipes for different oilfield wellbore applications. The wells may have a vertical, inclined, horizontal, or combination trajectories to deliver steam to the formation. Flow control devices are deployed in the plurality of tubulars to distribute steam. There are two primary methods of conformance (heat and flow) control: 1) tubing-deployment and 2) liner or casing deployment.
Tubing deployment (1) has flow control devices integrally connected to the tubing and the tubing is deployed inside casing or liner. For tubing deployment, steam exits the tubing via a tubing deployed flow control device(s) and enters the tubing-liner annulus. After entering the tubing-liner annulus, the steam then passes through the liner and enters the open hole or formation. Packers may be used with tubing deployment to direct and control the steam movement into the formation.
Liner or casing deployment (2) has flow control devices integrally connected to the liner or casing, and the liner and casing is deployed in open hole. For liner or casing deployment, steam is delivered with open-ended tubing (i.e. without flow control devices) into the liner or casing. Steam exits the liner or casing via a liner or casing deployed flow control device and enters the formation or open hole.
The flow control devices support uniform and/or targeted distribution of heat from the tubing into either the tubing-liner-annular space or formation. A plurality of packers may also be installed on the tubulars to effect hydraulic isolation of various wellbore segments in either the tubing-liner annulus or the liner-open hole annulus. The intent of this hydraulic isolation is the improvement of heat delivery uniformity to the wellbore-formation interface.
However, many factors can negatively affect the function of the steam injection system. For example, conventional flow control devices with large outside diameters increase friction and drag forces when inserting or pulling the tubing in a wellbore, which in turn, may increase the likelihood that the tubing and completion hardware will get stuck in a horizontal section of a wellbore (e.g., due to sand, scale, asphaltenes, etc.) and damaged due to being stuck. These conventional FCDs with large outside diameters also hinder fishing or other equipment recovery operations because they reduce the diametrical clearance available for such operations.
As another example, conventional mixers, which may be coupled to FCDs, lead to non-uniform steam splitting.
As another example, conventional packers may not provide an effective hydraulic seal (e.g., especially when the steam temperature is higher than 300° F.) and may not be able to direct the steam to the targeted portion of the formation or wellbore. Non-uniform heating can substantially impact the economics of the field development, oil production response, and create non-uniform steam breakthrough in the production wellbores. Furthermore, the steam injectors inject the volume of steam at high temperatures (>300° F.), which may result in deterioration of sealing element(s) of packers.
Diagnosis of equipment integrity is crucial to ensure the reliability and integrity of the steam injection system. Furthermore, steam conformance control in the steam injection and cyclic steam stimulation wellbores is crucial for formation heat management in heavy oil fields.
Thus, there continues to be a need for improved flow control devices, mixers, and sealing assemblies of packers for use in steam injection for hydrocarbon recovery.